SSI Back Money Last Installment?

Yes i was just wondering about my last SSI Installment ! I got my first one on 5/4/2010, my second one on 11/02/2010 Now from what they say our installments come every 6 months. Well May 2011 is 6 months and i'm suppose to get the rest and last of whats coming to me from my SSI Back Money, which is around 5700.00. Do you think i will get it around May 2, 2011 or will they make me wait cause its kinda a big amount!. My last 2 were direct deposited ! I just hope they dont screw me over or around ! Cause it would be nice to get all my bills paid off and get ahead at least for a couple months ! Thanks